Films have been traditionally used to provide barrier properties in single-use items including, but not limited to, articles of clothing in general, protective apparel, health care related products including surgical drapes, gowns, and sterile wrap and personal care absorbent products such as diapers, training pants, incontinence garments, sanitary napkins, bandages, and the like. In personal care absorbent products such as infant diapers and adult incontinence products, films are used as the outer covers with the purpose of preventing body wastes from contaminating the clothing, bedding, and other aspects of the surrounding environment of use. In the area of protective apparel including hospital gowns and other clean room garments, films are used to prevent exchange of microorganisms between the wearer and the patient. These films are usually one to two mils in thickness and have a basis weight of approximately 0.7 to 1.5 ounces per square yard. Polyolefin films are most commonly used in such areas.
One of the significant disadvantages in the utilization of films as barrier materials in most, if not all, of these types of products is that the films do their job too well. That is, they form a complete barrier. Complete barriers of this type create an entirely new problem in that they block the egress of water vapor from the person or item which the film enwraps. Accordingly, those wearing garments formed from such materials tend to rapidly become quite uncomfortable due to a build-up of water vapor which is given off by the individual but not allowed to pass through the film. The water vapor remains between the individual and the garment or item made from the material. The individual rapidly develops a feeling of being "sweaty" or "sticky" as the relative humidity in that confined area builds up and water vapor condenses therein.
In response to this problem, those of skill in the art have attempted to manufacture protective garments and other items where passage of microbes is undesirable from materials which allow the passage of water vapor. Such materials include, for example, nonwoven webs and laminates thereof as discussed in detail in U.S. Pat. No. 4,041,203 to Brock et al. This patent is hereby incorporated herein by reference in its entirety.
Microporous varieties of films, either by themselves or incorporated in laminates, have also been used in such products in an attempt to provide articles with more garment-like attributes, such as the ability to reduce the relative humidity underneath the garment, thus maintaining a higher degree of comfort for the wearer.
However, the use of nonwoven webs and/or microporous films in certain protective apparel has not been without difficulties. For example, utilization of such materials has generated concerns about their ability to prevent transfer of microorganisms because the size of microorganisms such as viruses and bacteria are typically much smaller than the pores of microporous films. Nonwoven web materials, typically, also are characterized by passageways therethrough which, while they may retard the progress of microbes, do not guarantee complete barrier properties with respect to them. For these reasons, neither of these arrangements has proven to be completely satisfactory in view of the fact that they do not form a complete barrier for microbes.
Therefore, there remains a distinct need for a material which allows the passage of water vapor therethrough while effectively forming a barrier to the passage of small pathogens such as viruses, bacteria, cysts and nematodes. If such a material were a fabric such as a spunbonded or meltblown nonwoven web, it could be used alone or as one layer of a laminate to provide an overall material which would have effective microbial barrier properties, breathability (that is, allow passage of an adequate amount of water vapor) and tactile feel.